The present invention relates to decorative and protective coatings for articles and which provide a desirable metallic appearance.
Decorative and protective coatings are widely employed on various articles and may be applied by various techniques. On metal articles, electroplating has been extensively utilized to provide chromium, zinc and brass plated surfaces which provide coatings which are both protective and decorative. In some instances, these electroplated coatings are chemically treated to enhance their corrosion and/or chemical resistance and/or to provide decorative finishes. In other instances, a clear lacquer or resin coating is applied. In some applications, colored organic coatings are applied directly to the substrate.
With synthetic resin articles, electroplating cannot be employed without first developing a conductive surface. Thus, chemical or electroless plating and vacuum metallizing are widely employed; however, development of a deposit of sufficient thickness to provide good protective coating is slow and expensive so that electroplating is frequently employed as a second step. Metal-filled organic resin coatings also are sometimes employed to provide a metallic appearance.
The techniques for applying organic coatings are varied, but spray applications predominate in usage. Such spray techniques can be quite inefficient because a substantial portion of the sprayed composition will not deposit on the article or will deposit unevenly. With articles having a conductive surface, electrostatic spray techniques greatly improve the efficiency of the coating operation.
It is an object of the present invention to provide a novel method for developing coatings with highly desirable metallic appearance at relatively low cost.
It is also an object to provide such a method which is applicable to both metallic and non-metallic substrates.
Another object is to provide such a method in which the coating exhibits good wear resistance and substantive uniformity of coloration.